I Don't Know What To Charge?!?

So I had a lady contact me through my facebook page and she told me that she is a cake decorator herself but she's 'old school' and has never worked with gumpaste or fondant. She said that she's going to be making a three tier underwater themed cake for her daughters birthday but she was wondering if I could make some fondant or gumpaste characters for it so she didn't have to buy plastic ones for it. She was asking me if I could make a dolphin, octopus, mermaid, crab and some small fish. I told her I could do it and ship them to her, but I have no clue what I should charge her. What sounds reasonable? Help me please! Thank you!

AI agree with the formula above, but if you aren't sure about the mark up percentage, etc, take a look at some of the toppers on etsy. That will give you an idea of what people are asking for the types of figures you plan to do.